Optical spectroscopy of two-dimensional layered (C_6H_5C_2H_4-NH_3)_2-PbI_4 perovskite

Abstract

We report on optical spectroscopy (photoluminescence and photoluminescence excitation) on twodimensional self-organized layers of (C6H5C2H4 − N H3)2P bI4 perovskite. Temperature and excitation power dependance of the optical spectra gives a new insight into the excitonic and phononic properties of this hybrid organic/inorganic semiconductor. In particular, exciton-phonon interaction is found to be more than one order of magnitude higher than in GaAs QWs. As a result, photoluminescence emission lines have to be interpreted in the framework of a polaron model. PACS numbers: Valid PACS appear hereOptical properties of soft materials have attracted much attention for years thanks to their potential applications in optoelectronics devices. In particular, these last years, an increasing number of studies are dedicated on hybrid organic-inorganic materials[1], due to the possibility of combining the properties both of inorganic materials (high mobility, electrical pumping, band engineering) and of organic materials (low cost technology, high luminescence quantum yield at room temperature). In this context, organic-inorganic perovkites, having a chemical formula (R − NH3) 2 MX 4 where R is an organic chain, M is a metal and X a halogen, represent a natural hybrid system. Such perovskites present a great flexibility in their optical properties: the spectral position of the excitonic transitions can be tailored by substituting different halides X [2, 3], the photoluminescence efficiency can be tailored by changing the organic part R [4]. This kind of perovskites has been studied both in the framework of fundamental studies [2,3,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24] and of applications in optoelectronic as the active material in a distributed feedback laser for example [25]. Recently the strong coupling regime between the perovskite exciton and the optical mode of a Pérot-Fabry microcavity has been demonstrated at room temperature in the UV range [5] and in the visible range [6,7]. The physical properties of these new polaritons have now to be investigated. In particular, the demonstration of polariton-polariton interactions which lead to polariton scattering would be a breakthrough for the physics of these new devices in the context of the low threshold polariton lasers [26,27,28]. To evaluate these possibilities, a good knowledge of the perovskite material electronic properties is needed. As an example, the energy of the phonons and the strength of the electron-phonon coupling will indicate whether an efficient relaxation of perovskite polaritons is conceivable. Additionally, the origin of the different perosvkite luminescence lines has to be clarified to improve the knowledge about the exciton which couples to the cavity mode. .In this paper, we report on the optical properties of a particular perovskite molecule, namely [bi-(phenethylammonium) tetraiodoplumbate]: (C 6 H 5 C 2 H 4 − N H 3 ) 2 − P bI 4 (named PEPI), absorbing and emitting in the green part of the visible range. Photoluminescence (PL) ...

Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells

“…Subsequently, a slower decay of the PB of n=2 QWs also matches well with a relative slower formation of the large-n QWs PB. This relatively slower exciton localisation time is fitted to be ~50 ps.The rapid energy transfer process in the perovskite MQWs can essentially avoid the exciton quenching effect presented in previously reported 2D perovskites 6,7 . Figure 1h shows the light-intensity-dependent PLQE of the NFPI7 film under a 445 nm cw laser excitation.…”

“…The rapid energy transfer process in the perovskite MQWs can essentially avoid the exciton quenching effect presented in previously reported 2D perovskites 6,7 . Figure 1h shows the light-intensity-dependent PLQE of the NFPI7 film under a 445 nm cw laser excitation.…”

“…However, the efficiency of their electroluminescence is limited by nonradiative recombination associated with defects and leakage current due to incomplete surface coverage [6][7][8][9] . Here we demonstrate a solution-processed perovskite light-emitting diode (LED) based on self-organised multiple quantum wells (MQWs) with excellent film morphology.…”

“…The 2D L2MX4 perovskites generally have good film-formation properties 13 . Nevertheless, the PLQEs of the 2D perovskites are rather low at room temperature, owing to fast exciton quenching rates 6,7 . LEDs based on the 2D perovskites have been attempted, while the devices are either very low in efficiency or only operational at cryogenic temperatures [16][17][18] .…”

Temperature changes of the exciton transition energy in lead di-iodide nanofilms

“…It explains hasty development of technologies for preparation and investigations of physical properties both of bulk lead di-iodide crystals [3,4] and low-dimensional [5], in particular, hybrid nonorganic -organic heterostructures based on it [6][7][8][9][10]. The latter are especially interesting due to combination of properties inherent to materials of both types as well as availability of spatial confinement (SC) effects.…”